DESCRIPTION: This is a competing continuation application requests funds to continue studies pertaining to the identification, cloning and characterizatio of enzymes involved in the biosynthesis of 9-cis-retinoic acid. The main hypothesis of the proposed work is that 9-cis-retinoic acid is synthesized by the oxidation of 9-cis-retinol to 9-cis-retinal which is then further oxidized to 9-cis-retinoic acid. Specifically, the aims of this proposal focus on the characterization of 9-cis-retinol dehydrogenase.